Karakuri Zoushi Ayatsuri Sakon EP7 - The Izu Two-Faced Oni - Part IV

Sakon deduces that Yagisawa committed suicide to protect the identity of Sato, Mai's mother who killed her abusive husband in the puppet mansion 16 years ago and who has been managing Mai under an assumed identity. Sakon reveals that it was Sato who killed Sugiyama because he was blackmailing her.